Developed between 1984 and 1987 (by coauthor Alan J. Witten) at the Oak Ridge National Laboratory in Tennessee, GDT has also been used to image the skeleton of seismosaurus, the largest known dinosaur, in the New Mexico desert; to detect tunnels beneath the demilitarized zone separating North and South Korea; and to find buried drums of toxic waste in the clean-up of two dump sites in Michigan and Minnesota.